We present a simple fabrication technique using a hydrophobic composite elastomer for patterning an SU-8-based rib waveguide Bragg grating filter via solvent-assisted microcontact molding (SAMIM). The proposed technique utilizes a two-layered composite stamp made of polydimethylsiloxane and hard polydimethylsiloxane, which enables both the rib waveguide and surface relief grating structure to be patterned simultaneously. The SAMIM method realizes patterning at ambient temperatures with the weight of the mold applying all the pressure necessary. By allowing the mold to absorb solvent when in contact with the polymer, the solvent dissolves or swells the polymer's surface, creating the desired pattern. This composite mold successfully demonstrates the SAMIM creation of the SU-8 rib waveguide and gratings, paving the way for a facile and efficient reproduction of a polymeric rib waveguide grating filter. Based on experimental results, the stamp demonstrates an operational life span in excess of 10 successful replications, utilizing a Bragg grating test pattern with a grating period of ~492 nm, a depth of ~250 nm, and a total length of 12 mm. The resulting waveguides show a band-rejection gain of −17 dB at the center wavelength of 1545 nm and a 3-dB bandwidth of 2.5 nm.
A polymeric SU8 rib waveguide Bragg grating filterfabricated using reactive ion etching (RIE) and solvent assisted
microcontact molding (SAMIM) is presented. SAMIM is one kind of soft lithography. The technique is unique in which
that a composite hPDMS/PDMS stamp was used to transfer the grating pattern onto an inverted SU8 rib waveguide
system. The composite grating stamp can be used repeatedly several times with degradation. Using this stamp and
inverter rib waveguide structure, the Bragg grating filter fabrication can be significantly simplified.
A flexible high-resolution sensor capable of measuring the distribution of both shear and pressure at the plantar interface are needed to study the actual distribution of this force during daily activities, and the role that shear plays in causing plantar ulceration. We have previously developed a novel means of transducing plantar shear and pressure stress via a new microfabricated optical system. However, a force image algorithm is needed to handle the complexity of construction of two-dimensional planar pressure and shear images. Here we have developed a force image algorithm for a micromachined optical bend loss sensor. A neural network is introduced to help identify different load shapes. According to the experimental result, we can conclude that once the neural network has been well trained, it can correctly identify the loading shape. With the neural network, our micromachined optical bend loss Sensor is able to construction the two-dimensional planar force images.